I have a Scientific Atlanta 2100 modem that's giving me problem. I have purchased a Motorola SB 6121 and Comcast sent a Cisco DPC3008. I was able to set the Scientific Atlanta modem to bridge mode myself, but the Motorola SB6121 and the Cisco DPC3008 does not have a bridge mode option. I have spent over two hours on the phone with Comcast support, and the techs that I have spoken to have no idea what I am talking about. I have the external interface of a Juniper firewall behind the cable modem that handles all public NATs to inside PCs when I'm not home, so I need to have a modem that I can put in bridge mode. Can someone please point me in the right direction?
the reason they say to put wireless gateways(built in wireless) in bridgemode is because that is basically a router... and a router to a router can cause issues so you put one in bridge mode to allow the other to handle the duties. Of course for the general user you probably wont dont need to do this.
you know the modem is "bridged" already because you cannot unplug and plug in a new device. you always have to reset the modem when a new device is plugged into it before it will work.
Those SA modems i have seen that before, though I do believe the default is bridged, older modems may have some settings like that. most modems now I don't believe have a way to change it, or I just have not seen it. different manuf though different options.
"bridge mode" is only applicable to gateways. These are combined modem/router, and this option refers to choosing whether they operate as a router or a bridge. In the case of an ordinary cable modem, they always act as a bridge, so there's no option to select.